 /*******************************************************************************
  * Copyright (c) 2000, 2006 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.internal;

 import org.eclipse.core.runtime.IConfigurationElement;
 import org.eclipse.ui.IActionDelegate;
 import org.eclipse.ui.IViewActionDelegate;
 import org.eclipse.ui.IViewPart;
 import org.eclipse.ui.WorkbenchException;

 /**
  * This class extends regular plugin action with the
  * additional requirement that the delegate has
  * to implement interface IViewActionDeelgate.
  * This interface has one additional method (init)
  * whose purpose is to initialize the delegate with
  * the view part in which the action is intended to run.
  */
 public final class ViewPluginAction extends PartPluginAction {
     private IViewPart viewPart;

     /**
      * This class adds the requirement that action delegates
      * loaded on demand implement IViewActionDelegate
      */
     public ViewPluginAction(IConfigurationElement actionElement,
             IViewPart viewPart, String id, int style) {
         super(actionElement, id, style);
         this.viewPart = viewPart;
         registerSelectionListener(viewPart);
     }

     /* (non-Javadoc)
      * Method declared on PluginAction.
      */
     protected IActionDelegate validateDelegate(Object obj)
             throws WorkbenchException {
         if (obj instanceof IViewActionDelegate) {
             return (IViewActionDelegate) obj;
         } else {
             throw new WorkbenchException(
                     "Action must implement IViewActionDelegate"); //$NON-NLS-1$
 }
     }

     /* (non-Javadoc)
      * Method declared on PluginAction.
      */
     protected void initDelegate() {
         super.initDelegate();
         ((IViewActionDelegate) getDelegate()).init(viewPart);
     }

     /**
      * Returns true if the view has been set
      * The view may be null after the constructor is called and
      * before the view is stored. We cannot create the delegate
      * at that time.
      */
     public boolean isOkToCreateDelegate() {
         return super.isOkToCreateDelegate() && viewPart != null;
     }
     
     /* (non-Javadoc)
      * @see org.eclipse.ui.internal.PluginAction#dispose()
      */
     public void dispose() {
         unregisterSelectionListener(viewPart);
         super.dispose();
     }
 }

